Corrosion of metal surfaces is a problem with many dimensions. Severe corrosion over long periods of time can destroy the integrity of metal structures. Consequently, various methods have been developed to prevent or limit the attack on metals. However, even a minor amount of corrosion on fresh metal surfaces can be a problem during the manufacturing of various types of equipment. Therefore, fresh metal surfaces may be protected temporarily until a more permanent protection can be provided or another manufacturing step is carried out. The degree of protection need not be great for short periods of time, but if temporary coatings are applied it is usually necessary to remove them before further processing of the metal. Depending upon the coating used, removing them may require solvents which present significant costs or disposal problems. Also, the coatings themselves may contain materials which should be avoided for environmental reasons. Consequently, there remains a need for improved temporary coatings for corrosion prevention.
The problems associated with such coatings are discussed in U.S. Pat. No. 4,315,957, which discloses a wax composition which can be removed by a steam-water mixture, thereby avoiding the use of solvents.
Various waxes, greases, soaps and related compounds have been used for temporary protection of fresh metal surfaces as is indicated in U.S. Pat. No. 4,315,957. It is characteristic of such materials that they can be fairly easily removed while more permanent coatings cannot.
Ideally, a temporary coating should provide corrosion protection for a short period, say about 1-7 days. The coating should be easy to apply and easy to remove, while avoiding materials which present environmental problems.
The present invention employs a different method than those discussed above and achieves the desired results, as will be seen in the description which follows.